Subject: kern/4514: Bug in PMTU discovery and/or routing code?
To: None <>
From: Michael Graff <>
List: netbsd-bugs
Date: 11/17/1997 01:31:55
>Number:         4514
>Category:       kern
>Synopsis:       Bug in PMTU discovery and/or routing code?
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people (Kernel Bug People)
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Nov 16 22:35:01 1997
>Originator:     Michael Graff
>Organization:  yes, we do know everything
>Release:        Fri Nov 14 12:29:46 EST 1997
System: NetBSD 1.3_ALPHA NetBSD 1.3_ALPHA (KECHARA) #1: Fri Nov 14 12:29:46 EST 1997 i386

When using PMTU discovery, routes are added as MTUs are discovered:

Destination        Gateway            Flags     Refs     Use    Mtu  Interface
default   UGS        42  1641364      -  de0
localhost          localhost          UH         11   195227      -  lo0
192.80.44          link#1             UC          0        0      -  de0
kechara            localhost          UGHS        5   202657      -  lo0
tel-aran-rhiod     link#1             UHL         3     3793    508  de0
amberdrake         00:80:ad:03:6c:62  UHL         2    38320    508  de0
aerie              00:80:ad:03:6c:62  UHL         4    18972    508  de0      link#1             UHL         1      955      -  de0

Now, there are no open sockets to tel-aran-rhiod.  The route was added
when PMTU discovered the route.  Shouldn't the Refs be 0, and the route

This is bad, since with a web server talking to random PPP dialup clients,
the route map fills fast.
Turn on PMTU and make a TCP connection
No idea...